Recently, many copying machines are combined with automatic document feeders and devices for further processing after copying such as binding or punching the copied sheets in order to automate the process. The automatic document feeder is placed on a document tray of the copying machine, for example, for transporting a plurality of documents one by one onto the document tray of the copying machine. The device for further processing after copying is for carrying out a process after copying, such as stapling, punching, etc., on every predetermined number of sheets fed from the copying machine.
The device disclosed in Japanese Laid-Open Publication 144370/1990 (Tokukaihei 2-144370) as an example of the conventional device for further processing after copying has the following arrangement. As shown in FIG. 89(a), first, the copied sheets S being transported from the side of a main body 301 are stacked on a stapler plate 302 where the copied sheets S are aligned. Then, the sheets S are bound by a stapler 303 provided within the device. Thereafter, the bound set of sheets S is sandwiched between discharge rollers 304 and 305 to be discharged onto a discharge tray 306.
The device is also provided with first and second transport paths 308a and 308b, whose lengths are different, placed between an entry opening 307 for the sheets S on the side of the main body 301 and the stapler plate 302. Furthermore, a deflector 309 is provided at a branch point between the first and the second transport paths 308a and 308b so as to switch the transport path for the sheet either to the first path 308a or to the second path 308b. Here, the first path 308a is set longer than the second path 308b, and the downstream of the first path 308a joins again the second path 308b. A discharge roller 310 is provided at the end of the path for releasing the sheets S onto the stapler plate 302 through the path.
As shown in FIG. 89(a), when binding a plurality of sets of sheets S, the device for further processing after copying operates as follows. While a predetermined binding operation is carried out on a first set of sheets S on the stapler plate 302, a first sheet S.sub.1 of the next set fed from the rain body 301 is transported through the first path 308a, and a second sheet S.sub.2 of the next set is transported through the second path 308b. With this arrangement, the second sheet S.sub.2 is stacked on the first sheet S.sub.1 so as to be discharged onto the stapler plate 302 through the discharge roller 310 at the same time as shown in FIG. 89(b). As a result, the time loss due to the time required for binding the first set of sheets S can be reduced, thereby permitting a faster binding process.
The first and the second sheets S.sub.1 and S.sub.2 released onto the stapler plate 302 at the same time are sandwiched between the rollers 304 and 305. In this state, the ends of the sheets S.sub.1 and S.sub.2 are respectively aligned by rotating the discharge roller 305 in an opposite direction to its rotation direction for discharging the sheets S.
As described, the first transport path 308a is set longer than the second transport path 308b so as to release the first and the second sheets S.sub.1 and S.sub.2 onto the stapler plate 302 at the same time. This arrangement enables a faster process for binding a plurality of sheets S. However, in the case of adopting sheets S of a large size, the transport paths must be set long in order to maintain the above arrangement. This makes the size of the device larger. In order to avoid the device being made larger, the first and the second transport paths 308a and 308b may be curved instead of being straight. However, this makes the transport paths for the sheets S complicated, and is likely to create the problem of lowering the quality of the bound set of sheets S by being creased.
With the above arrangement, when aligning the ends of the discharged sheets S.sub.1 and S.sub.2, the sheets S.sub.1 and S.sub.2 are sandwiched between the rollers 304 and 305, and are aligned by rotating the discharge roller 305 in the opposite direction. However, it is difficult to precisely align a stack of the sheets S.sub.1 and S.sub.2, thereby lowering the quality of the bound set of sheets S.
The device for further processing after copying having the above configuration is shown in FIGS. 90(a)(b) and FIG. 91. In the case of the staple mode wherein the sheets S being transported from the side of the main body 301 are bound before being discharged out of the device, the copied sheets S, which have been transported from the side of the main body 301 through the transport path 311, are aligned on the stapler plate 312 as shown in FIG. 90(a). Then, the sheets S are bound by the stapler 313 provided within the device, thereafter the bound set of sheets S is discharged onto a discharge tray 316 using the rotation of a discharge roller 314 and the forward motion of a push-out member 315.
On the other hand, in the case of the offset mode wherein the sheets S being transported from the side of the main body are discharged one by one out of the device without being further processed after copying, the sheets S are discharged as follows. As shown in FIG. 90(b), a driven roller 317 placed above the discharge roller 314 is rotated so as to be in contact with the discharge roller 314. Then, the copied sheets S being transported through the transport path 311 from the side of the main body 301 are sandwiched between the rollers 314 and 317 to be directly discharged onto the discharge tray 316.
Further, the device shown in FIG. 91 is provided with an offset tray 324 for placing thereon the sheets S in the offset mode separately from a staple tray 329 for placing thereon the sheets S in the staple mode. With this arrangement, in the case of the offset mode, with a path switching operation of the deflector 322, first the sheets S being transported from the side of the main body 301 are passed through the first transport path 321a. Then, the sheets S are sandwiched between the discharge rollers 323 to be discharged onto the discharge tray 324. On the other hand, in the staple mode, with the path switching operation of the deflector 322, the sheets S being transported through the second transport path 321b are aligned on the stapler plate 325. Then, the sheets S are bound by the stapler 326 provided in the device, and are discharged onto the discharge tray 329 with the rotation of the discharge roller 327 and the forward motion of the push-out member 328.
In the conventional device shown in FIGS. 90(a)(b), the sheet transporting direction in the offset mode is different from the sheet transporting direction in the staple mode, and the sheets S are discharged onto the same discharge tray 316 in both modes. However, since the tray angle of the discharge tray 316 is constant, the ability to discharge sufficient in both modes is difficult to be obtained. Moreover, there is a level difference between the discharge roller 314 and the stapler plate 312 which causes the buckling and the creasing of the bound set of sheets S.
On the other hand, in the device of FIG. 91 provided with the offset tray 324 and the stapler tray 329, the tray angles are separately set for the trays 324 and 329 so as to satisfy the ability to discharge in both modes. However, since the relative positions between the stapler tray 329 and the stapler plate 325 are not improved, the problem that the quality of the sheets is lowered due to the creasing of the bound set of sheets S still exists.
Furthermore, the discharge tray 316 of the device shown in FIGS. 90(a)(b) has a recessed portion 316a shown in FIG. 93 at the corner on the side of the device so that the stapled corners St of the bound set of sheets S drop by the dead weight of the corners St into the recessed portion 316a. In this way, the preciseness in aligning the bound sets of sheets S on the discharge tray 316 can be improved.
As described, the alignment of the bound sets of sheets S on the discharge tray 316 can be improved by making the stapled corners St of the bound sets of sheets S drop into the recessed portion 316a by the dead weight of the corners St. However, with the above arrangement, the number of the corners St drop into the recessed portion 316a differs depending on the number of the bound sets of sheets S to be placed on the discharge tray 316 and on the material used for the sheets S. For this reason, in the case where the number of the bound sets of sheets S to be placed is large, or thicker paper is used for the sheets S, since there is a limit which the recessed portion 316a can accept the stapled corners St dropped by the dead weight of the corners St, the stapled corners St may be pushed back, which reduces the preciseness in aligning the bound sets of sheets S. The acceptable number of the stapled corners St to be dropped into the recessed portion 316a may be slightly improved by making larger the area of the recessed portion 316a. However, the area of the recessed portion 316a to be formed on the discharge tray 316 also has a limit. Therefore, it is difficult to accurately drop the stapled corners St into the recessed portion 316a.